Invasive Fungal Skull Base Osteomyelitis After Dental Extraction: Cranial Neuropathy and Diagnostic Discordance Between Superficial Cultures and Repeated Deep Tissue Biopsies

A 59-year-old man with diabetes mellitus developed progressive skull base osteomyelitis following left maxillary third molar extraction, with symptom onset within 2 days. The disease progressed with multiple cranial neuropathies, orbital apex syndrome, and intracranial extension. Repeated superficial cultures predominantly yielded Pseudomonas aeruginosa , whereas repeated fungal cultures were largely nondiagnostic. Serial deep tissue biopsies demonstrated invasive fungal infection, establishing the definitive diagnosis and guiding subsequent antifungal therapy. Despite repeated surgical debridement, facial palsy and complete visual loss persisted at the most recent follow-up. This case suggests that progressive skull base infection should not be managed according to superficial culture results alone. Instead, repeated deep tissue biopsy should be considered when microbiologic findings remain discordant with the clinical course.